This invention relates to a turnstile control mechanism of the type which permits single person access through the turnstile on the actuation of a release mechanism but which will bar access to further persons passing through the turnstile until the release mechanism is again actuated.
Most turnstile control mechanisms would operate satisfactorily if they were permitted to operate without significant pressure being applied to the turnstile arms. However, this is usually not the case and persons pressing on the turnstile arms tend to apply a significant load to the release mechanism. Damage can be caused to the mechanism, particularly when a load is being applied to the arms at the same time as the release mechanism is being operated.
Most turnstile control mechanisms include a hub fixed to rotate with the turnstile arms and some form of release mechanism which is engagable with or disengagable from the hub. The diameter of the hub is generally significantly less than the diameter of the rotational arc of the outer ends of the turnstile arms. Thus, due to the principle of mechanical advantage, the load applied to the release mechanism is significantly larger than the load applied to the arms by the person pressing against the arms. Where the release mechanism comprises a solenoid or like electrically operated release catch it will need to be relatively powerful to overcome the load applied to it in this manner. It is often found that the release mechanism will fail over a period of time.
A further problem with prior art turnstile mechanism is that the rotation of the turnstile is not damped in any significant manner. Thus, where persons are passing through the turnstile rotate the turnstile arms on their way through, the release mechanism is placed under undue strain as it clicks into its locked position. This too can result in early failure of the control mechanism.